Holographic recording medium and optical element containing the same

Abstract

The present invention relates to a holographic recording medium and an optical element including the same. The holographic recording medium not only has excellent optical recording characteristics, but also exhibits transparent optical characteristics and excellent reliability even in high temperature and high humidity environments.

Description

[Technical Field]

[0001] [Cross-reference of related applications] This application claims priority rights based on Korean Patent Application No. 10-2022-0146042 dated November 4, 2022, and Korean Patent Application No. 10-2022-0146046 dated November 4, 2022, and all content disclosed in the documents of said Korean Patent Applications is included as part of the specification of this application.

[0002] This application relates to a holographic recording medium and an optical element including the same. [Background technology]

[0003] Holographic recording media record information by changing the refractive index within the holographic recording layer during the exposure process, and then reproduce the information by reading the difference in refractive index recorded in this way.

[0004] In this regard, photopolymer compositions can be used in the manufacture of holograms. Photopolymers can easily store optical interference patterns as holograms by photopolymerization of photoreactive monomers. Therefore, photopolymers can be used in a variety of fields, such as smart devices like mobile devices, components of wearable displays, automotive accessories (e.g., head-up displays), holographic fingerprint recognition systems, holographic optical elements having the functions of optical lenses, mirrors, deflectors, filters, diffusion screens, diffraction members, light guides, waveguides, projection screens and / or masks, media and light diffusers for optical memory systems, optical wavelength dividers, and reflective and transmissive color filters.

[0005] Specifically, the photopolymer composition for hologram production comprises a polymer matrix, photoreactive monomers, and a photoinitiator system. A photopolymer layer produced from such a composition is then irradiated with laser interference light to induce localized photopolymerization of the monomers.

[0006] Such localized photopolymerization processes lead to refractive index modulation, which in turn generates a diffraction grating. The refractive index modulation value (Δn) is influenced by the thickness of the photopolymer layer and the diffraction efficiency (DE), and the angular selectivity widens as the thickness decreases.

[0007] Recently, there has been a growing demand for materials that offer high diffraction efficiency and can stably maintain holograms. As a result, various attempts are being made to manufacture holographic recording media that are thin yet possess high diffraction efficiency and refractive index modulation values.

[0008] On the other hand, when holographic recording media are used as optical elements in applications such as mobile devices and automotive accessories (e.g., head-up displays), they are exposed to high-temperature and high-humidity environments. In this case, deformation of the diffraction grating occurs, causing image distortion or preventing the intended function from being performed. Therefore, there is a need to develop photopolymer layers and holographic recording media containing them that exhibit minimal deformation of the diffraction grating despite the heat and moisture of the operating environment and offer superior reliability. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] According to one embodiment of the present invention, a hologram recording medium is provided.

[0010] According to another embodiment of the present invention, an optical element including a holographic recording medium is provided. [Means for solving the problem]

[0011] The following describes a specific embodiment of the present invention, including a holographic recording medium and an optical element containing the same.

[0012] In this specification, unless otherwise specified, “hologram recording medium” means a medium (or media) capable of recording optical information across the entire visible light range and ultraviolet range (e.g., 300 to 1,200 nm) through an exposure process. Therefore, the hologram recording medium in this specification may mean a medium on which optical information has been recorded, or a pre-recording medium in a state capable of recording optical information. The holograms in this specification may include all visual holograms, such as in-line (Gabor) holograms, off-axis holograms, full-aperture transfer holograms, white light transmission holograms ("rainbow holograms"), Denisyuk holograms, off-axis reflection holograms, edge-lit holograms, or holographic stereograms.

[0013] In this specification, in relation to the environmental conditions in which a holographic recording medium or an element containing the same is placed, “high temperature” may mean a temperature of 60°C or higher. For example, high temperature may mean a temperature of 65°C or higher, 70°C or higher, 75°C or higher, 80°C or higher, 85°C or higher, or 90°C or higher, and there is no particular upper limit, but for example, it may be 110°C or lower, 105°C or lower, 100°C or lower, 95°C or lower, 90°C or lower, 85°C or lower, or 80°C or lower. If temperature affects the characteristics of a substance, article or each component, unless a different temperature is specifically mentioned, the temperature conditions under which the characteristics are measured or described may mean room temperature (for example, a temperature in the range of about 15 to 30°C, which is a temperature at which no cooling or heating occurs).

[0014] Furthermore, in this specification, in relation to the environmental conditions in which a holographic recording medium or an element containing the same is placed, "high humidity" may mean a relative humidity of 80% or higher. For example, high humidity conditions may mean conditions that satisfy a relative humidity of 85% or higher, 90% or higher, or 95% or higher. When humidity affects the characteristics of a substance, article, or each component, unless otherwise specified, the humidity conditions under which the characteristics are measured or described may be lower relative humidity conditions than high humidity conditions, for example, relative humidity conditions in the range of 15% or higher and less than 80%, specifically, relative humidity conditions where the lower limit is 20% or higher, 25% or higher, 30% or higher, 35% or higher, 40% or higher, and the upper limit is 75% or lower, 70% or lower, 65% or lower, or 60% or lower.

[0015] Furthermore, in this specification, high temperature / high humidity conditions may mean environmental conditions that satisfy one or more of the described high temperature conditions and high humidity conditions.

[0016] According to one embodiment of the present invention, a holographic recording medium is provided comprising a polymer matrix or precursor formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a photopolymer layer comprising a fluorine compound, wherein the peak variation calculated by the following formula 3 is 3% or less, and the adhesive strength measured under conditions of a peel angle of 180° and a peel rate of 5 mm / sec after laminating an optically transparent adhesive layer to the photopolymer layer and storing it for 72 hours at a temperature of 60°C and 90% relative humidity is 500 gf / 2.5 cm or more.

[0017] Peak change = {|1-A1 / A0|} × 100 (Equation 3) In Equation 3, A0 is the wavelength of the lowest transmittance of the holographic recording medium for the wavelength range of 300 to 1,200 nm, and A1 is the wavelength of the lowest transmittance measured after the holographic recording medium has been exposed to conditions of 60°C and 90% relative humidity for 72 hours.

[0018] The inventors of the present invention have completed the present invention by confirming that, when a specific photopolymer layer is included, it is possible to provide a holographic recording medium that exhibits improved optical recording characteristics while also showing high reliability and high transparency of optical properties even in high temperature / high humidity environments.

[0019] Hereinafter, a holographic recording medium and an optical element including a holographic recording medium according to one embodiment of the present invention will be described in detail.

[0020] A holographic recording medium according to one embodiment of the present invention comprises a polymer matrix or its precursor formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained thereby; and a photopolymer layer containing a fluorine compound.

[0021] The photopolymer layer may be a pre-recording photopolymer layer capable of recording optical information, or it may be a photopolymer layer in which optical information has been recorded.

[0022] A photopolymer layer with recorded optical information can be manufactured by irradiating a pre-recorded photopolymer layer with object light and reference light. When a pre-recorded photopolymer layer is irradiated with object light and reference light, the photoinitiator system remains inactive in the canceling interference region due to the interference length of the object light and reference light, preventing photopolymerization of photoreactive monomers. In the reinforcing interference region, the activated photoinitiator system causes photopolymerization of photoreactive monomers. In the reinforcing interference region, the photoreactive monomers are continuously consumed, creating a concentration difference between the canceling and reinforcing interference regions. As a result, the photoreactive monomers in the canceling interference region diffuse into the reinforcing interference region. At this time, the fluorine-based plasticizer moves in the opposite direction to the photoreactive monomers. Since the photoreactive monomers and the photopolymers formed from them have a higher refractive index than the polymer matrix and fluorine-based compound, a spatial change in refractive index occurs in the photopolymer layer, and this spatial refractive index modulation in the photopolymer layer generates a lattice. Such lattice surfaces act as reflective surfaces that reflect incident light due to differences in refractive index. After hologram recording, when light of a specific wavelength is incident in the direction of the reference light, the Bragg condition is met, and the light diffracts in the direction of the original object light, allowing the hologram optical information to be reconstructed.

[0023] Therefore, if the photopolymer layer is in its pre-recording state, the photopolymer layer may contain a polymer matrix or its precursor in which photoreactive monomers, photoinitiators, and fluorinated compounds are randomly dispersed.

[0024] In contrast, if optical information is recorded in the photopolymer layer, the photopolymer layer may contain a photopolymer and a fluorine-based compound distributed to form a polymer matrix and lattice.

[0025] The photopolymer layer is formed from a photopolymer composition comprising a polymer matrix or its precursor formed by crosslinking a siloxane polymer containing silane functional groups and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system; and a fluorine-based compound.

[0026] The polymer matrix serves as a support for the photopolymer layer and is formed by crosslinking a siloxane polymer containing silane functional groups (Si-H) and a (meth)acrylic polyol. Specifically, the polymer matrix is ​​formed by crosslinking a (meth)acrylic polyol with a siloxane polymer containing silane functional groups. More specifically, the hydroxyl groups of the (meth)acrylic polyol can form crosslinks with the silane functional groups of the siloxane polymer through a hydrosilylation reaction. The hydrosilylation reaction can be carried out rapidly at room temperature (for example, at a temperature in the range of about 15 to 30°C without heating or cooling) under a Pt-based catalyst. Therefore, the hologram recording medium of one embodiment of the present invention can improve manufacturing efficiency and productivity by employing a polymer matrix that can be rapidly crosslinked at room temperature as a support.

[0027] The polymer matrix, with its flexible main chain of siloxane polymers, can enhance the mobility of components contained in the photopolymer layer (e.g., photoreactive monomers or plasticizers). Furthermore, the siloxane bonds, which have excellent heat and moisture resistance, can easily ensure the reliability of the photopolymer layer on which optical information is recorded and the holographic recording medium containing it.

[0028] The polymer matrix can have a relatively low refractive index, which can play a role in enhancing the refractive index modulation of the photopolymer layer. For example, the upper limit of the refractive index of the polymer matrix may be 1.53 or less, 1.52 or less, 1.51 or less, 1.50 or less, or 1.49 or less. The lower limit of the refractive index of the polymer matrix may be, for example, 1.40 or more, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more. In this specification, "refractive index" may be a value measured with an Abbe refractometer at 25°C.

[0029] The photopolymer layer may contain the crosslinked polymer matrix described above, or may contain its precursor. If the photopolymer layer contains a precursor of the polymer matrix, it may contain a siloxane polymer, a (meth)acrylic polyol, and a Pt-based catalyst.

[0030] Siloxane polymers may, for example, include repeating units represented by the following chemical formula 2 and terminal groups represented by the following chemical formula 3. [ka] In chemical formula 2, multiple R 11 and R 12 These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. k is an integer between 1 and 10,000.

[0031] [ka] In chemical formula 3, multiple R 13 ~R 15 These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. R 11 ~R 15 At least one of them is hydrogen.

[0032] In chemical formula 3, -(O)- indicates that when the Si of the terminal group represented by chemical formula 3 bonds to the repeating unit represented by chemical formula 2, the bond occurs either via oxygen (O) or directly without oxygen (O).

[0033] In the present specification, the "alkyl group" may be a straight-chain, branched-chain or cyclic alkyl group. As non-limiting examples, in the present specification, the "alkyl group" includes methyl, ethyl, propyl (e.g., n-propyl, isopropyl, etc.), butyl (e.g., n-butyl, isobutyl, tert-butyl, sec-butyl, cyclobutyl, etc.), pentyl (e.g., n-pentyl, isopentyl, neopentyl, tert-pentyl, 1,1-dimethyl-propyl, 1-ethyl-propyl, 1-methyl-butyl, cyclopentyl, etc.), hexyl (e.g., n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methylpentyl, 3,3-dimethylbutyl, 1-ethyl-butyl, 2-ethylbutyl, cyclopentylmethyl, cyclohexyl, etc.), heptyl (e.g., n-heptyl, 1-methylhexyl, 4-methylhexyl, 5-methylhexyl, cyclohexylmethyl, etc.), octyl (e.g., n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, etc.), nonyl (e.g., n-nonyl, 2,2-dimethylheptyl, etc.), and the like.

[0034] As an example, R in Chemical Formula 2 and Chemical Formula 3 11 ~R 15 is methyl or hydrogen, and at least two of the plurality of R 11 ~R 15 may be hydrogen. More specifically, as the siloxane-based polymer, R 11 and R 12 in Chemical Formula 2 are methyl and hydrogen, respectively, and R 13 ~R 15 in Chemical Formula 3 are each independently methyl or hydrogen (e.g., polymethylhydrogensiloxane having a terminal group of a trimethylsilyl group or a dimethylhydrosilyl group); a part of R 11 and R 12 in Chemical Formula 2 are methyl and hydrogen, respectively, and the remaining R 11 and R 12 are all methyl, and R 13 ~R 15Compounds in which each is independently methyl or hydrogen (e.g., poly(dimethylsiloxane-co-methylhydrosiloxane) whose terminal group is a trimethylsilyl group or a dimethylhydrosilyl group; or R of chemical formula 2) 11 and R 12 All are methyl, and R in chemical formula 3 13 ~R 15 The compound may be one in which at least one of the terminal groups is hydrogen and the rest are independently methyl or hydrogen (for example, a polydimethylsiloxane in which one or all of the terminal groups are dimethylhydrosilyl groups).

[0035] Siloxane compounds can, for example, have a number-average molecular weight (Mn) in the range of 200 to 4,000. Specifically, the lower limit of the number-average molecular weight of the siloxane polymer may be, for example, 200 or more, 250 or more, 300 or more, or 350 or more, and the upper limit may be, for example, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less, 1,500 or less, or 1,000 or less. When the number-average molecular weight of the siloxane polymer satisfies the above range, it is possible to prevent problems such as the siloxane polymer volatilizing and the degree of matrix crosslinking decreasing during the crosslinking process with (meth)acrylic polyol carried out at room temperature or above, or the siloxane polymer having poor compatibility with other components of the photopolymer composition and resulting in phase separation with such components, thereby enabling the holographic recording medium formed from the photopolymer composition to exhibit excellent optical recording properties and excellent durability under high temperature / high humidity conditions.

[0036] The number-average molecular weight refers to the number-average molecular weight (in g / mol) in polystyrene equivalent, measured by GPC (Gel Permeation Chromatography). The process of measuring the polystyrene equivalent number-average molecular weight using GPC can utilize commonly known analytical instruments, detectors such as differential index detectors, and analytical columns, and can apply commonly used temperature conditions, solvents, and flow rates. Specific examples of measurement conditions include a temperature of 25°C, tetrahydrofuran solvent, and a flow rate of 1 mL / min.

[0037] (Meth)acrylic polyols can mean polymers in which one or more, specifically two or more, hydroxyl groups are bonded to the main chain or side chain of a (meth)acrylate polymer. In this specification, "(meth)acrylic(system)" refers to acrylic(system) and / or methacrylic(system) unless otherwise specified, and is a term that encompasses all acrylic(system), methacrylic(system), or mixtures of acrylic(system) and methacrylic(system).

[0038] The (meth)acrylic polyol may be a homopolymer of (meth)acrylate monomers having hydroxyl groups, a copolymer of (meth)acrylate monomers having two or more hydroxyl groups, or a copolymer of a (meth)acrylate monomer having hydroxyl groups and a (meth)acrylate monomer not having hydroxyl groups. In this specification, unless otherwise specified, "polymer" is a term that encompasses all random copolymers, block copolymers, and graft copolymers.

[0039] Examples of (meth)acrylate monomers having a hydroxyl group include hydroxyalkyl (meth)acrylate or hydroxyaryl (meth)acrylate, where the alkyl is an alkyl group having 1 to 30 carbon atoms, and the aryl may be an aryl group having 6 to 30 carbon atoms. Examples of (meth)acrylate monomers not having a hydroxyl group include alkyl (meth)acrylate monomers or aryl (meth)acrylate monomers, where the alkyl is an alkyl group having 1 to 30 carbon atoms, and the aryl may be an aryl group having 6 to 30 carbon atoms.

[0040] (Meth)acrylic polyols can, for example, have a weight-average molecular weight (Mw) in the range of 150,000 to 1,000,000. The weight-average molecular weight refers to the weight-average molecular weight in polystyrene terms, measured by the GPC method as described above. For example, the lower limit of the weight-average molecular weight may be 150,000 or more, 200,000 or more, or 250,000 or more, and the upper limit may be, for example, 900,000 or less, 850,000 or less, 800,000 or less, 750,000 or less, 700,000 or less, 650,000 or less, 600,000 or less, 550,000 or less, 500,000 or less, or 450,000 or less. When the weight-average molecular weight of the (meth)acrylic polyol satisfies the above range, the polymer matrix fully performs its function as a support, resulting in minimal degradation of the recording characteristics for optical information even after extended use. This imparts sufficient flexibility to the polymer matrix, improving the fluidity (mobility) of the components contained in the photopolymer composition (e.g., photoreactive monomers or plasticizers), thereby minimizing the degradation of the recording characteristics for optical information.

[0041] To adjust the crosslinking density of (meth)acrylic polyols with siloxane polymers to a level advantageous for ensuring the functionality of holographic recording media, the hydroxyl group equivalent of (meth)acrylic polyols can be adjusted to an appropriate level.

[0042] Specifically, the hydroxyl group (-OH) equivalent of (meth)acrylic polyols may be, for example, in the range of 500 to 3,000 g / equivalent. More specifically, the lower limit of the hydroxyl group (-OH) equivalent of (meth)acrylic polyols may be 600 g / equivalent or more, 700 g / equivalent or more, 800 g / equivalent or more, 900 g / equivalent or more, 1000 g / equivalent or more, 1100 g / equivalent or more, 1200 g / equivalent or more, 1300 g / equivalent or more, 1400 g / equivalent or more, 1500 g / equivalent or more, 1600 g / equivalent or more, 1700 g / equivalent or more, or 1750 g / equivalent or more. Furthermore, the upper limit of the hydroxyl group (-OH) equivalent of (meth)acrylic polyols may be 2900 g / equivalent or less, 2800 g / equivalent or less, 2700 g / equivalent or less, 2600 g / equivalent or less, 2500 g / equivalent or less, 2400 g / equivalent or less, 2300 g / equivalent or less, 2200 g / equivalent or less, 2100 g / equivalent or less, 2000 g / equivalent or less, or 1900 g / equivalent or less. The hydroxyl group (-OH) equivalent of (meth)acrylic polyols is the equivalent amount (g / equivalent) per hydroxyl functional group, and is the value obtained by dividing the weight-average molecular weight of (meth)acrylic polyols by the number of hydroxyl functional groups per molecule. The smaller the equivalent value, the higher the density of functional groups, and the larger the equivalent value, the lower the density of functional groups. When the hydroxyl group (-OH) equivalent of the (meth)acrylic polyol satisfies the above range, the polymer matrix has an appropriate crosslinking density and fully performs its role as a support, improving the fluidity of the components contained in the photopolymer layer. This prevents the breakdown of the diffraction grating interface generated after recording, maintains the initial refractive index modulation value at an excellent level even after time has passed, and minimizes the degradation of recording characteristics for optical information.

[0043] (Meth)acrylic polyols can have a glass transition temperature (Tg) in the range of -60 to -10°C, for example. Specifically, the lower limit of the glass transition temperature may be, for example, -55°C or higher, -50°C or higher, -45°C or higher, -40°C or higher, -35°C or higher, -30°C or higher, or -25°C or higher, and the upper limit may be, for example, -15°C or lower, -20°C or lower, -25°C or lower, -30°C or lower, or -35°C or lower. When the above glass transition temperature range is satisfied, the glass transition temperature can be lowered without significantly reducing the modulus of the polymer matrix, thereby increasing the mobility (fluidity) of other components in the photopolymer composition and improving the moldability of the photopolymer composition. The glass transition temperature can be measured using known methods, such as DSC (Differential Scanning Calorimetry) or DMA (dynamic mechanical analysis).

[0044] The refractive index of a (meth)acrylic polyol may be, for example, 1.40 or more and less than 1.50. Specifically, the lower limit of the refractive index of a (meth)acrylic polyol may be, for example, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more, and the upper limit may be, for example, 1.49 or less, 1.48 or less, 1.47 or less, 1.46 or less, or 1.45 or less. When a (meth)acrylic polyol has a refractive index within the range described above, it can contribute to enhancing refractive index modulation. The refractive index of a (meth)acrylic polyol is a theoretical refractive index and can be calculated using the refractive index of the monomers used in the production of the (meth)acrylic polyol (value measured using an Abbe refractometer at 25°C) and the fraction (molar ratio) of each monomer.

[0045] (Meth)acrylic polyols and siloxane polymers can be used such that the molar ratio (SiH / OH) of silane functional groups (Si-H) of the siloxane polymer to the hydroxyl groups (-OH) of the (meth)acrylic polyol is between 0.80 and 3.5. In other words, the type and content of siloxane polymers and (meth)acrylic polyols can be selected to satisfy the molar ratio during the formation of the polymer matrix. The lower limit of the molar ratio (SiH / OH) may be, for example, 0.81 or higher, 0.85 or higher, 0.90 or higher, 0.95 or higher, 1.00 or higher, or 1.05 or higher, and the upper limit may be, for example, 3.4 or lower, 3.3 or lower, 3.2 or lower, 3.1 or lower, 3.05 or lower, or 3.0 or lower. When the above range of molar ratio (SiH / OH) is satisfied, the polymer matrix is ​​crosslinked with an appropriate crosslinking density, improving reliability under high temperature / high humidity conditions and enabling the achievement of a sufficient refractive index modulation value.

[0046] The Pt-based catalyst may, for example, be Karstedt's catalyst. The polymer matrix precursor may, if necessary, additionally include non-metallic catalysts such as rhodium-based, iridium-based, rhenium-based, molybdenum-based, iron-based, nickel-based, alkali metal or alkaline earth metal-based, Lewis acid-based, or carbene-based catalysts, in addition to the Pt-based catalyst.

[0047] On the other hand, the photoreactive monomers may include compounds having a higher refractive index than the polymer matrix in order to achieve the refractive index modulation described above. However, it is not limited to all photoreactive monomers in the photopolymer layer having a higher refractive index than the polymer matrix; at least some of the photoreactive monomers may have a higher refractive index than the polymer matrix in order to achieve a high refractive index modulation value. As an example, the photoreactive monomers may include monomers with refractive indices of 1.50 or higher, 1.51 or higher, 1.52 or higher, 1.53 or higher, 1.54 or higher, 1.55 or higher, 1.56 or higher, 1.57 or higher, 1.58 or higher, 1.59 or higher, or 1.60 or higher and 1.70 or lower.

[0048] The photoreactive monomer may include one or more monomers selected from the group consisting of monofunctional monomers having one photoreactive functional group and polyfunctional monomers having two or more photoreactive functional groups. In this case, the photoreactive functional group may be, for example, a (meth)acryloyl group, a vinyl group, or a thiol group. More specifically, the photoreactive functional group may be a (meth)acryloyl group.

[0049] Monofunctional monomers include, for example, benzyl (meth)acrylate (M1182, Miwon Co., Ltd., with a refractive index of 1.5140), benzyl 2-phenyl acrylate, phenoxybenzyl (meth)acrylate (M1122, Miwon Co., Ltd., with a refractive index of 1.565), phenol (ethylene oxide) (meth)acrylate (phenol (EO) (meth)acrylate, M140, Miwon Co., Ltd., with a refractive index of 1.516), and phenol (ethylene oxide) 2 (meth)acrylate (phenoxybenzyl acrylate). It may contain one or more substances selected from the group consisting of ol(EO)2(meth)acrylate (M142, Miwon Co., Ltd., with a refractive index of 1.510), O-phenylphenol(ethylene oxide)(meth)acrylate (M1142, Miwon Co., Ltd., with a refractive index of 1.577), phenylthioethyl(meth)acrylate (M1162, Miwon Co., Ltd., with a refractive index of 1.560), and biphenylmethyl(meth)acrylate.

[0050] Polyfunctional monomers include, for example, bisphenol A (ethylene oxide). 2~10 Di(meth)acrylate (bisphenol A(EO) 2~10(Meth)acrylate, M240 with refractive index 1.537, M241 with refractive index 1.529, M244 with refractive index 1.545, M245 with refractive index 1.537, M249 with refractive index 1.542, M2100 with refractive index 1.516, M2101 with refractive index 1.512 (Miwon Co.), Bisphenol A epoxy di(meth)acrylate (PE210 with refractive index 1.557, PE2120A with refractive index 1.533, PE2120B with refractive index 1.534, PE2020C with refractive index 1.539, PE2120S with refractive index 1.556 (Miwon Co.), Bisphenol A epoxy di(meth)acrylate (HR6022 with refractive index 1.600, HR6040 with refractive index 1.600, H It may contain one or more substances selected from the group consisting of R6042 (Miwon), modified bisphenol full orange (meth)acrylate (HR6060 with a refractive index of 1.584, HR6100 with a refractive index of 1.562, HR6200 with a refractive index of 1.530, Miwon), tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate (M370 with a refractive index of 1.508, Miwon), phenol novolac epoxy (meth)acrylate (SC6300 with a refractive index of 1.525, Miwon), and cresol novolac epoxy (meth)acrylate (SC6400 with a refractive index of 1.522, SC6400C with a refractive index of 1.522, Miwon).

[0051] The photopolymer layer may contain 50 to 300 parts by weight of photoreactive monomers per 100 parts by weight of the polymer matrix. For example, the lower limit of the photoreactive monomer content may be 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, or 90 parts by weight or more, and the upper limit may be 300 parts by weight or less, 280 parts by weight or less, 250 parts by weight or less, 220 parts by weight or less, 200 parts by weight or less, 190 parts by weight or less, or 180 parts by weight or less. Meeting the above ranges is advantageous in ensuring excellent optical recording characteristics and durability in high temperature / high humidity environments.

[0052] In this specification, the polymer matrix content refers to the combined content (by weight) of the (meth)acrylic polyol and siloxane polymer that form the matrix. In other words, the polymer matrix content refers to the total content including the polymer matrix formed by the crosslinking of the (meth)acrylic polyol and siloxane polymer, and the polymer matrix precursor that is not partially crosslinked.

[0053] The photopolymer layer contains a photoinitiator system. A photoinitiator system can refer to a photoinitiator that enables polymerization to begin upon exposure to light, or it can refer to a combination of a photosensitizer and a coinitiator.

[0054] The photopolymer layer may include a photosensitizer and a co-initiator as a photoinitiator system.

[0055] For example, photosensitive dyes can be used as photosensitizers. Specifically, photosensitive dyes include, for example, silicon rhodamine compounds, sulfonium derivatives of ceramidonine, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose bengal, thionine, basic yellow, pinacyanol chloride, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, Quinaldine Red, and crystal violet. You may use one or more of the following: violet, Brilliant Green, Astrazon Orange G, Darrow Red, Pyronin Y, Basic Red 29, Pyrylium I (iodide), Safranin O, Cyanine, Methylene Blue, Azure A, and BODIPY.

[0056] As an example, as a photosensitive dye, cyanine dyes such as Cy3 and Cy5 (H-Nu640, Spectra Group Limited) can be used, or safranin O can be used.

[0057] The photopolymer layer may contain a photosensitive dye in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the polymer matrix. Specifically, the lower limit of the photosensitive dye content may be, for example, 0.05 parts by weight or more, 0.07 parts by weight or more, or 0.10 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above ranges are met, it is advantageous to exhibit an appropriate polymerization reaction rate and ensure the desired optical recording characteristics.

[0058] The co-initiator may be an electron donor, an electron acceptor, or a mixture thereof.

[0059] As an example, the photopolymer layer may contain an electron donor as a co-initiator. The electron donor may include, for example, a borate anion represented by the following chemical formula 4.

[0060] BX 1 X 2 X 3 X 4 (Chemical formula 4) In chemical formula 4, X 1 ~X 4 Each of these is independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, and X 1 ~X 4 At least one of them is not an aryl group.

[0061] When an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group is substituted, it may be substituted with one or more selected from the group consisting of halogens and alkoxy groups having 1 to 5 carbon atoms.

[0062] Specifically, X 1 ~X 3 Each of these is independently halogen-substituted or unsubstituted methyl, ethyl, propyl, n-butyl, n-pentyl, n-hexyl, cyclobutyl, cyclopentyl, cyclohexyl, ethenyl, propenyl, phenyl, methylphenyl, methoxyphenyl, naphthyl, methylnaphthyl, or methoxynaphthyl, and X 4 This may be n-butyl, n-pentyl, or n-hexyl. More specifically, the borate anion represented by chemical formula 4 may be, for example, triphenylbutyl borate anion.

[0063] The cation bonded to the borate anion is one that does not absorb light and may be an alkali metal cation or a quaternary ammonium cation. A quaternary ammonium cation means an ammonium cation in which nitrogen (N) is substituted with four substituents, and each of the four substituents may independently be a C1-C40 alkyl group, a C6-C30 aryl group, a C6-C40 arylalkyl group, or a C2-C40 alkyl group linked via an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3).

[0064] As an electron donor, for example, commercially available butyryl choline triphenylbutylborate (Borate V, Spectra Group) can be used.

[0065] As an example, a photopolymer layer may contain an electron acceptor as a co-initiator. The electron acceptor may include onium salts such as sulfonium salts, iodonium salts, or mixtures thereof.

[0066] As an example, an iodonium salt can be used as the electron acceptor. For example, commercially available H-Nu254 (Spectra Group) can be used as the electron acceptor.

[0067] The photopolymer layer may contain a co-initiator in an amount ranging from 0.05 to 10 parts by weight per 100 parts by weight of the polymer matrix. Specifically, the lower limit of the co-initiator content may be, for example, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, or 0.5 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above ranges are met, it is advantageous to exhibit an appropriate polymerization reaction rate and ensure the desired optical recording characteristics.

[0068] The photoinitiator system may include additional photoinitiators to remove the color of the photosensitive dye and to react all unreacted photoreactive monomers after light irradiation for recording. Examples of photoinitiators include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, thioxanthone derivatives, amine derivatives, diazonium salts, sulfonium salts, iodonium salts, sulfonic acid esters, imidosulfonates, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η6-benzene)(η5-cyclopentadienyl)iron(II), benzointosylate, 2,5-dinitrobenzyltosylate, N-tosylphthalimide, or mixtures thereof.More specifically, the photoinitiators include 1,3-di(t-butyldioxycarbonyl)benzophenone, 3,3',4,4''-tetrakis(t-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-mercaptobenzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one (product name: Irgacure651 / manufacturer: BASF), 1-hydroxy- Cyclohexyl-phenyl-ketone (product name: Irgacure184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure369 / manufacturer: BASF), bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium (product name: Irgacure784 / manufacturer: BASF), Evecryl Examples include, but are not limited to, P-115 (manufactured by SK entis), Cyracure UVI-6970, Cyracure UVI-6974, Cyracure UVI-6990 (manufactured by Dow Chemical Co. in USA), Irgacure 264, Irgacure 250 (manufactured by BASF), CIT-1682 (manufactured by Nippon Soda Co., Ltd.), or mixtures thereof.

[0069] The photopolymer layer contains a fluorine-based compound as a plasticizer.

[0070] Plasticizers facilitate refractive index modulation during the manufacturing of holographic recording media. More specifically, plasticizers lower the glass transition temperature of the polymer matrix, improving the fluidity of photoreactive monomers. They have low refractive index and non-reactive properties, are uniformly distributed within the polymer matrix, and when photoreactive monomers that have not been photopolymerized move, they move in the opposite direction, contributing to refractive index modulation. Furthermore, plasticizers can also contribute to improving the moldability of photopolymer compositions.

[0071] Fluorine-based compounds can have a low refractive index of 1.45 or less in order to perform the plasticizer function described above. Specifically, the upper limit of the refractive index may be, for example, 1.44 or less, 1.43 or less, 1.42 or less, 1.41 or less, 1.40 or less, 1.40 or less, 1.39 or less, 1.38 or less, or 1.37 or less, and the lower limit of the refractive index may be, for example, 1.30 or more, 1.31 or more, 1.32 or more, 1.33 or more, 1.34 or more, or 1.35 or more. By using fluorine-based compounds with a lower refractive index than the photoreactive monomers described above, the refractive index of the polymer matrix can be made even lower, and the refractive index modulation with the photoreactive monomers can be made larger.

[0072] By including a fluorine-based compound represented by the following chemical formula 1 in the photopolymer layer, it is possible to provide a holographic recording medium that not only has excellent optical recording properties but also excellent reliability and high transparency optical properties even in high temperature / high humidity environments. [ka]

[0073] In chemical formula 1, Z 1 and Z 2 These are, independently, -O-, -S-, or -NH-, R 1 ~R 4 One of these is a fluorine-containing substituent, which is a C1-C20 alkyl group substituted with two or more fluorines, a C3-C30 cycloalkyl group substituted with two or more fluorines, or an aryl group substituted with two or more fluorines. R 1 ~R 4If is not a fluorine-containing substituent, each is independently a C1-C20 alkyl group, a C3-C30 cycloalkyl group, a C4-C30 heterocycloalkyl group, a C7-C40 cycloalkylalkyl group, a C6-C30 aryl group, a C4-C30 heteroaryl group, or a C7-C40 arylalkyl group, or a substituent in which one or more -CH2- groups of the substituent are replaced with -O-, -S-, or -NH-.

[0074] More specifically, the fluorine-based compound represented by chemical formula 1 exhibits sufficient low refractive index, thereby increasing refractive index modulation with photoreactive monomers and effectively fulfilling its role as a basic plasticizer that improves the diffusivity of components in the photopolymer composition. Furthermore, the fluorine-based compound represented by chemical formula 1 exhibits minimal migration to the photopolymer layer surface, even at high temperatures and high humidity environments, making it highly resistant to heat and moisture. It is less prone to decomposition even under high temperature / high humidity conditions, thus improving reliability in high temperature / high humidity environments. In addition, the fluorine-based compound represented by chemical formula 1 shows excellent compatibility with components having high refractive indices, ensuring highly transparent optical properties through its excellent resistance to heat and humidity.

[0075] In chemical formula 1, R 1 ~R 4 At least one of them is a fluorine-containing substituent. For example, R 1 This may be a fluorine-containing substituent.

[0076] The fluorine-containing substituent may be a C1-C20 alkyl group substituted with two or more fluorines, a C3-C30 cycloalkyl group substituted with two or more fluorines, or an aryl group substituted with two or more fluorines.

[0077] Specifically, the fluorine-containing substituent may be a linear alkyl group having 1 to 20 carbon atoms substituted with two or more fluorines, a cycloalkyl group having 3 to 12 carbon atoms substituted with two or more fluorines, or an aryl group having 6 to 14 carbon atoms substituted with two or more fluorines.

[0078] More specifically, fluorine-containing substituents are -(CH2) a (CF2) b CHF2, -(CH2) a (CF2) b CF3 may be a decafluorocyclohexyl group or a pentafluorophenyl group. Here, a is an integer from 0 to 3, an integer from 0 to 2, or an integer from 0 to 1, and b may be an integer from 0 to 19, an integer from 0 to 15, an integer from 0 to 14, an integer from 0 to 13, an integer from 0 to 12, or an integer from 0 to 11.

[0079] As an example, a fluorine-containing substituent is -(CH2) a (CF2) b CHF2, -(CH2) a (CF2) b In the case of CF3 or decafluorocyclohexyl groups, it is possible to provide holographic recording media with low haze while contributing to large refractive index modulation.

[0080] In chemical formula 1, R 1 ~R 4 If R is not a fluorine-containing substituent, 1 ~R 4 Each of these can independently be an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a heterocycloalkyl group having 4 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which one or more of the -CH2- groups of the substituent are replaced with -O-, -S-, or -NH-.

[0081] Specifically, in chemical formula 1, R 1 ~R 4 If R is not a fluorine-containing substituent, 1 ~R 4Each of these can independently be a linear alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a heterocycloalkyl group having 4 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, a heteroaryl group having 4 to 12 carbon atoms, an arylalkyl group having 7 to 16 carbon atoms, or -(R 5 -Y 1 ) c -R 6 It may be. -(R 5 -Y 1 ) c -R 6 In R 5 R is an alkylene group having 1 to 6 carbon atoms. 6 This is an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms, Y 1 is -O- or -S-, c may be an integer from 1 to 12, and when c is 2 or greater, R 5 They may be the same or different from one another.

[0082] More specifically, in chemical formula 1, R 1 ~R 4 If R is not a fluorine-containing substituent, 1 ~R 4 These are, independently, ethyl group, propyl group, butyl group, pentyl group, hexyl group, phenyl group, benzyl group, pyridinyl group, pyrimidinyl group, methoxymethyl group, methoxyethyl group, methyl mercaptoethyl group, methylaminoethyl group, -(CH2CH2O) c1 CH3, -CH2O (CH2CH2O) c2 CH3 may be a cyclohexyloxyethyl group, a cyclohexyl mercaptoethyl group, or a phenyloxyethyl group. Here, c1 is an integer from 1 to 5, and c2 is an integer from 1 to 4.

[0083] A fluorine-based compound represented by chemical formula 1 may contain one or more fluorine-based compounds selected from the group consisting of fluorine-based compounds represented by the following chemical formulas 1-1 to 1-9. [ka]

[0084] In Chemical Formula 1-1, Z a1 and Z b1 are each independently -O-, -S-, or -NH-, R a1 and R b1 are each independently CF3 or CHF2, R c1 and R c2 are each independently an alkylene group having 1 to 6 carbon atoms, Y a1 and Y a2 are each independently -CH2-, -O-, -S-, or -NH-, R d1 and R d2 are each independently an alkylene group having 1 to 4 carbon atoms, R e1 and R e2 are each independently hydrogen, an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, or a phenyl group, p1 and p2 are each independently an integer from 0 to 9, and q1 and q2 are each independently an integer from 0 to 3.

Chemical Formula

[0085] In Chemical Formula 1-2, Z a2 and Z b2 are each independently -O-, -S-, or -NH-, R a2 is CF3 or CHF2, R c3 ~R c5 are each independently an alkylene group having 1 to 6 carbon atoms, Y a3 ~Y a5 are each independently -CH2-, -O-, -S-, or -NH-, R d3~R d5 These are, independently, alkylene groups having 1 to 4 carbon atoms. R e3 ~R e5 Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyclohexyl group, or a phenyl group. p3 is an integer between 0 and 9, and q3 to q5 are each independent integers between 0 and 3. [ka]

[0086] In chemical formula 1-3, Z a3 and Z b3 These are, independently, -O-, -S-, or -NH-, R a3 , R b2 and R b3 These are, independently, CF3 or CHF2, R c6 This is an alkylene group having 1 to 6 carbon atoms. Y a6 These are -CH2-, -O-, -S-, or -NH-, R d6 This is an alkylene group having 1 to 4 carbon atoms. R e6 These are hydrogen, an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, or a phenyl group. R f1 and R f2 These are, independently, hydrogen or fluorine, p4 to p6 are each independent integers between 0 and 9, and q6 is an integer between 0 and 3. [ka]

[0087] In chemical formula 1-4, Z a4 and Z b4 These are, independently, -O-, -S-, or -NH-, R a4, R a5 , R b4 and R b5 These are, independently, CF3 or CHF2, R f3 ~R f6 These are, independently, hydrogen or fluorine, p7 to p10 are each independent integers from 0 to 9. [ka]

[0088] In chemical formula 1-5, Z a5 and Z b5 These are, independently, -O-, -S-, or -NH-, R a6 and R a7 These are, independently, CF3 or CHF2, R c7 and R c8 Each of these is an alkylene group having 1 to 6 carbon atoms, Y a7 and Y a8 These are, independently, -CH2-, -O-, -S-, or -NH-, R d7 and R d8 These are, independently, alkylene groups having 1 to 4 carbon atoms. R e7 and R e8 Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyclohexyl group, or a phenyl group. p11 to p12 are independent integers between 0 and 9, and q7 and q8 are independent integers between 0 and 3. [ka]

[0089] In chemical formula 1-6, Z a6 and Z b6These are, independently, -O-, -S-, or -NH-, R a8 ~R a10 These are, independently, CF3 or CHF2, R c9 This is an alkylene group having 1 to 6 carbon atoms. Y a9 These are -CH2-, -O-, -S-, or -NH-, R d9 This is an alkylene group having 1 to 4 carbon atoms. R e9 These are hydrogen, an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, or a phenyl group. p13 to p15 are independent integers from 0 to 9, and q9 is an integer from 0 to 3. [ka]

[0090] In chemical formula 1-7, Z a7 and Z b7 These are, independently, -O-, -S-, or -NH-, R b9 , R c10 and R d10 These are, independently, a decafluorocyclohexyl group, a phenyl group, a pyridinyl group, a pyrimidinyl group, or a methoxyethyl group. [ka]

[0091] In chemical formula 1-8, Z a8 and Z b8 These are, independently, -O-, -S-, or -NH-, R b10 , R c11 and R d11 These are, independently, a 2,2,3,3,4,4,5,5-oxafluoro-1-pentyl group, a decafluorocyclohexyl group, a phenyl group, or a methoxyethyl group. [ka]

[0092] In chemical formula 1-9, Z a9 and Z b9 These are, independently, -O-, -S-, or -NH-, R a11 and R b11 These are, independently, CF3 or CHF2, R c12 and R d12 These are, independently, a phenyl group or a benzyl group. p16 and p17 are each independent integers between 0 and 9.

[0093] The photopolymer layer may contain 20 to 200 parts by weight of a fluorine-based compound per 100 parts by weight of the polymer matrix. Specifically, the lower limit of the fluorine-based compound content may be, for example, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 35 parts by weight or more, 40 parts by weight or more, 45 parts by weight or more, 50 parts by weight or more, or 55 parts by weight or more, and the upper limit may be, for example, 200 parts by weight or less, 180 parts by weight or less, 150 parts by weight or less, 120 parts by weight or less, or 100 parts by weight or less. When the above range is met, it is possible to show a large refractive index modulation value after recording by a fluorine-based compound with a sufficiently low refractive index, without problems such as poor compatibility with the components contained in the photopolymer layer, eluting of some fluorine-based compounds onto the surface of the photopolymer layer, or poor haze, which is advantageous in ensuring excellent optical recording characteristics.

[0094] The photopolymer layer may contain additional additives such as defoaming agents.

[0095] The photopolymer layer may contain a silicone-based reactive additive as an antifoaming agent. Commercially available silicone-based reactive additives, such as Tego Rad 2500, can be used.

[0096] The content of additives, such as antifoaming agents, can be appropriately adjusted to a level that does not interfere with the function of the holographic recording medium.

[0097] The photopolymer layer may be formed from a photopolymer composition containing a solvent.

[0098] The solvent may be an organic solvent, or, for example, one or more organic solvents selected from the group consisting of ketones, alcohols, acetates, and ethers, but is not limited thereto. Specific examples of such organic solvents include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or isobutyl ketone; alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, or t-butanol; acetates such as ethyl acetate, i-propyl acetate, or polyethylene glycol monomethyl ether acetate; and one or more ethers selected from the group consisting of tetrahydrofuran or propylene glycol monomethyl ether.

[0099] The organic solvent may be added when the components of the photopolymer composition are mixed, or it may be added to the photopolymer composition while the components are dispersed or mixed in the organic solvent.

[0100] The photopolymer composition may contain a solvent such that the solid content concentration is 1 to 90% by weight. Specifically, the photopolymer composition may contain a solvent such that the solid content concentration is 20% or more by weight, 30% or more by weight, 50% or more by weight, or 60% or more by weight, and 85% or less by weight, 80% or less by weight, 75% or less by weight, or 70% or less by weight. Within this range, the photopolymer composition can exhibit appropriate flowability, form a coating film without defects such as stripes, and form a photopolymer layer that exhibits desired physical properties and surface characteristics without defects occurring during the drying and curing process.

[0101] The holographic recording medium of one embodiment, by including the above-described photopolymer layer, can exhibit excellent reliability even in high-temperature / high-humidity environments.

[0102] Specifically, in one embodiment, the hologram recording medium has a peak change of 3% or less, calculated by the following formula 3. Peak change = {|1-A1 / A0|} × 100 (Equation 3)

[0103] In Equation 3, A0 is the wavelength of the lowest transmittance of the holographic recording medium for the wavelength range of 300 to 1,200 nm, and A1 is the wavelength of the lowest transmittance measured after the holographic recording medium has been exposed to a temperature of 60°C and a relative humidity of 90% for 72 hours.

[0104] The peak shift describes the degree of wavelength shift in the minimum transmittance wavelength before and after high temperature / high humidity conditions. For example, if a holographic grating (e.g., a reflective hologram) is recorded to reflect light of a specific wavelength of 680 nm, the minimum transmittance will be at 680 nm. Then, if the transmittance is measured again after exposure to high temperature / high humidity conditions, the minimum transmittance may appear at 675 nm. In this case, according to Equation 1 above, there is considered to be a peak shift of less than 1%. Thus, depending on the conditions under which the holographic grating is driven or stored, a peak shift occurs in which the minimum transmittance wavelength shifts to shorter wavelengths as the spacing of the diffraction grating decreases (i.e., the diffraction grating contracts). Conversely, if the spacing of the holographic diffraction grating increases (diffraction grating expands), a peak shift may occur in which the minimum transmittance wavelength shifts to longer wavelengths. The degree of such peak shifts varies depending on the reliability of the diffraction grating.

[0105] In other words, a peak change of 3% or less means that deformation (shrinkage or expansion) of the diffraction grating can be suppressed so that the peak change remains 3% or less even when exposed to harsh conditions such as high temperature and high humidity. Such holographic recording media can provide good color reproduction and image clarity even when exposed to harsh conditions.

[0106] The peak change for the hologram recording medium in one embodiment may be, for example, 2.5% or less, 2.0% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, or 1.1% or less. The lower limit of the peak change is not particularly limited and may be 0% or more.

[0107] One embodiment of the holographic recording medium exhibits high durability against heat and moisture, and can maintain high adhesive strength even after aging in a high-temperature / high-humidity environment. Specifically, the holographic recording medium of one embodiment, with an optically transparent adhesive layer laminated to a photopolymer layer, is stored for 72 hours at a temperature of 60°C and a relative humidity of 90%, and then, when measured under conditions of a peel angle of 180° and a peel rate of 5 mm / sec, has an adhesive strength of 500 gf / 2.5 cm or more.

[0108] The type of optically transparent adhesive layer is not particularly limited and may be, for example, a rubber-based adhesive layer, an acrylic-based adhesive layer, or a silicone-based adhesive layer. The holographic recording medium of one embodiment is not limited to exhibiting excellent adhesion to all types of adhesive layers. However, the holographic recording medium of one embodiment can exhibit excellent adhesion to a variety of types of adhesive layers.

[0109] The lower limit of the adhesive strength may be, for example, 530 gf / 2.5 cm or more, 550 gf / 2.5 cm, 600 gf / 2.5 cm or more, 700 gf / 2.5 cm or more, 800 gf / 2.5 cm or more, 850 gf / 2.5 cm or more, 900 gf / 2.5 cm or more, 950 gf / 2.5 cm or more, 1000 gf / 2.5 cm or more, 1020 gf / 2.5 cm or more, 1050 gf / 2.5 cm or more, or 1100 gf / 2.5 cm or more. The method for measuring the adhesive strength can be found in the test examples described later. The upper limit of the adhesive strength is not particularly limited and may be 2500 gf / 2.5 cm or less.

[0110] The holographic recording medium of one embodiment exhibits excellent refractive index modulation, diffraction efficiency, and driving reliability despite having a thin photopolymer layer.

[0111] The thickness of the photopolymer layer may be, for example, in the range of 5.0 to 40.0 μm. Specifically, the lower limit of the thickness of the photopolymer layer may be, for example, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. The upper limit of the thickness may be, for example, 35 μm or less, 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, or 18 μm or less.

[0112] In one embodiment, the holographic recording medium may further include a substrate on at least one surface of the photopolymer layer. The type of substrate is not particularly limited, and any known in the relevant art can be used. For example, substrates such as glass, PET (polyethylene terephthalate), TAC (triacetyl cellulose), PC (polycarbonate), and COP (cycloolefin polymer) can be used.

[0113] A holographic recording medium of one embodiment can have high diffraction efficiency. For example, when a notch filter hologram is recorded on the holographic recording medium, it can have a diffraction efficiency of 70% or more. In this case, the thickness of the photopolymer layer may be, for example, 5 to 30 μm. Specifically, when a notch filter hologram is recorded, the diffraction efficiency may be 75% or more, 80% or more, 85% or more, 86% or more, 87% or more, or 88% or more. Thus, holographic recording media of other embodiments can achieve excellent diffraction efficiency even if they contain a thin photopolymer layer. Diffraction efficiency can be measured using the method described in the test examples below.

[0114] In one embodiment, even with a thin photopolymer layer thickness of 5 to 30 μm, the holographic recording medium can achieve refractive index modulation values ​​(Δn) of 0.020 or higher, 0.025 or higher, 0.026 or higher, 0.027 or higher, 0.028 or higher, 0.029 or higher, 0.030 or higher, 0.031 or higher, 0.032 or higher, 0.033 or higher, 0.034 or higher, or 0.035 or higher. The upper limit of the refractive index modulation value is not particularly limited, but for example, it may be 0.060 or lower. The refractive index modulation value can be measured by the method described in the test examples below.

[0115] On the other hand, holographic recording media tend to have opaque properties due to the incompatibility of components that mix components with low refractive indices and components with high refractive indices in order to record optical properties. However, a holographic recording media of one embodiment can exhibit highly transparent optical properties by using a fluorine-based compound with a specific structure that has excellent compatibility.

[0116] For example, the haze of the hologram recording medium may be 2% or less. The upper limit of the haze may be, for example, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, or 0.7% or less. The lower limit of the haze is not particularly limited and may be 0% or more. The haze can be measured by the method described in the test examples below.

[0117] One embodiment of the holographic recording medium is expected to provide a variety of optical elements that can be used even in environments where a lot of heat is generated or humidity is high, by exhibiting not only excellent optical recording characteristics and excellent durability in high temperature / high humidity environments, but also highly transparent optical characteristics.

[0118] The holographic recording medium of one embodiment is not limited thereto, but may be one on which a reflective hologram or a transmissive hologram is recorded.

[0119] For example, the diffraction grating of a photopolymer layer may be a reflective hologram grating. In the case of a transmissive hologram grating, since the diffraction grating is formed perpendicular to the plane of the substrate, the linear expansion coefficients of the substrate and the photopolymer have a greater influence on the deformation of the grating. In contrast, since a reflective hologram grating is formed horizontally to the plane of the substrate, the expansion or contraction of the volumetric hologram grating formed inside the photopolymer has a greater influence on image clarity than a mismatch in the linear expansion coefficients of the substrate and the diffraction grating. For this reason, reflective holograms are more suitable for holographic recording media with such peak change characteristics.

[0120] For example, the diffraction grating of the photopolymer layer may be formed parallel or horizontal to the bottom surface on which the substrate is placed. In this case, "parallel" or "horizontal" means substantially parallel or horizontal, and can mean that the fringe angle of the diffraction grating with respect to the bottom surface on which the substrate is placed is within an error range of ±5°, ±4°, ±3°, ±2°, or ±1°.

[0121] A holographic recording medium may have a notch filter structure in relation to its diffraction grating structure. In one embodiment, having a notch filter structure in a holographic recording medium means, for example, that the diffraction grating is not tilted (non-slanted) (substantially 0°) with respect to the substrate surface, such that the diffraction grating is parallel to the substrate surface. Such a holographic recording medium may have a structure in which two layers with different refractive indices (e.g., a high refractive index layer and a low refractive index layer) are alternately repeated. The two repeating layers may each have the same or different predetermined thicknesses. Such a non-slanted diffraction grating recording can be manufactured in a manner in which the incident angles of the incident object light and the reference light are the same with respect to the normal. In a non-slanted structure, the degree of deformation (e.g., shrinkage or expansion) under high temperature / high humidity conditions is more clearly observed than in a slantated structure, and it is less affected by the shrinkage and expansion of the substrate.

[0122] The applications of the holographic recording medium of one embodiment are not particularly limited. Non-limiting examples include applications that are likely to be exposed to high temperature / high humidity environments, specifically smart devices such as mobile devices, components of wearable displays, or automotive components (e.g., head-up displays).

[0123] On the other hand, a hologram recording medium according to one embodiment is manufactured by the step of applying a photopolymer composition to form a photopolymer layer, and by the step of irradiating a predetermined area of ​​the photopolymer layer manufactured in this way before recording with a coherent laser to selectively polymerize the photoreactive monomers contained in the photopolymer layer and record optical information, it can be manufactured in a form in which optical information is recorded.

[0124] In the step of forming the photopolymer layer, a photopolymer composition containing the above-described configuration can first be manufactured. When manufacturing the photopolymer composition, any commonly known mixer, stirrer, or similar device can be used to mix the components without any limitations. Such a mixing process may be carried out at temperatures in the range of 0°C to 100°C, 10°C to 80°C, or 20°C to 60°C.

[0125] In the step of forming the photopolymer layer, the prepared photopolymer composition can be applied to form a coating film made from the photopolymer composition. The coating film may be dried naturally at room temperature or at a temperature in the range of 30 to 80°C. This process can induce a hydrosilylation reaction between the hydroxyl group of the unreacted (meth)acrylic polyol and the silane functional group of the siloxane polymer.

[0126] The photopolymer layer produced by the step of forming the photopolymer layer may have a fluorine-based compound, a photoreactive monomer and a photoinitiator system, and additives added as needed, uniformly dispersed within the crosslinked polymer matrix.

[0127] Subsequently, when a coherent laser is irradiated onto the photopolymer layer during the optical information recording stage, polymerization of photoreactive monomers occurs in regions where reinforcement interference occurs, forming a photopolymer. In regions where cancellation interference occurs, polymerization of photoreactive monomers does not occur or is suppressed, resulting in the presence of photoreactive monomers. The unreacted photoreactive monomers then diffuse towards the photopolymer side where the concentration of photoreactive monomers is lower, causing refractive index modulation, which generates a diffraction grating. As a result, a hologram, or optical information, is recorded on the photopolymer layer containing the diffraction grating.

[0128] In one embodiment, the hologram recording medium can be provided in a state where the reaction of the photoreactive monomer is terminated and the color of the photosensitive dye is removed by a photobleaching step, which is performed after the step of recording the optical information, by irradiating the entire photopolymer layer on which the optical information is recorded with light.

[0129] For example, in the photobleaching stage, ultraviolet light (UVA) in the 320-400 nm range is irradiated to terminate the reaction of the photoreactive monomers and remove the color of the photosensitive dye.

[0130] On the other hand, according to another embodiment of the invention, a holographic recording medium is provided, comprising a polymer matrix or precursor thereof formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a photopolymer layer comprising a fluorine-based compound represented by the following chemical formula 1. [ka]

[0131] In chemical formula 1, Z 1 and Z 2 These are, independently, -O-, -S-, or -NH-, R 1 ~R 4 At least one of these is a fluorine-containing substituent, which is a C1-C20 alkyl group substituted with two or more fluorines, a C3-C30 cycloalkyl group substituted with two or more fluorines, or an aryl group substituted with two or more fluorines. R 1 ~R 4If is not a fluorine-containing substituent, each is independently either an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a heterocycloalkyl group having 4 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which one or more of the -CH2- groups of the substituent are replaced with -O-, -S-, or -NH- groups.

[0132] Holographic recording media according to other embodiments, by including a fluorine-based compound of a specific structure as a plasticizer, can exhibit improved optical recording characteristics while also demonstrating high reliability and high transparency of optical properties even in high-temperature / high-humidity environments.

[0133] Other embodiments of holographic recording media may, for example, exhibit high reliability even in high-temperature / high-humidity environments, such as having a peak change of 3% or less calculated by formula 3 above, and having an optically transparent adhesive layer laminated to a photopolymer layer, and exhibiting a high adhesive strength of 500 gf / 2.5 cm or more after storage at a temperature of 60°C and 90% relative humidity for 72 hours, with a peel angle of 180° and a peel rate of 5 mm / sec.

[0134] The polymer matrix or its precursor; photoreactive monomers and photoinitiator systems or photopolymers obtained therefrom; and fluorine-based compounds represented by chemical formula 1 included in the holographic recording medium of another embodiment can be the same as those included in the holographic recording medium of one embodiment. The polymer matrix or its precursor; photoreactive monomers and photoinitiator systems or photopolymers obtained therefrom; and fluorine-based compounds represented by chemical formula 1 have been described in detail above, so a detailed explanation is omitted here.

[0135] On the other hand, according to yet another embodiment of the present invention, an optical element including a holographic recording medium is provided.

[0136] Specific examples of optical elements include smart devices such as mobile devices, components for wearable displays, vehicle accessories (e.g., head-up displays), holographic fingerprint recognition systems, optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, diffracting members, light guides, waveguides, holographic optical elements that function as projection screens and / or masks, media and light diffusers for optical memory systems, optical wavelength dividers, and reflective and transmissive color filters.

[0137] An example of an optical element including a holographic recording medium is a holographic display device. A holographic display device includes a light source, an input unit, an optical system, and a display unit.

[0138] Specifically, the light source unit is the part that emits a laser beam used to provide, record, and reproduce three-dimensional image information of an object in the input unit and display unit.

[0139] The input section is where three-dimensional image information of an object to be recorded on the display unit is pre-inputted. Specifically, it allows input of three-dimensional information of an object, such as the intensity and phase of light in different spaces, to an electrically driven liquid crystal (SLM) Spatial Light Modulator (SLM), and this is the section where the input beam can be used.

[0140] The optical system may consist of mirrors, polarizers, beam splitters, beam shutters, lenses, etc. The optical system can distribute the laser beam emitted from the light source to an input beam that sends to the input unit, a recording beam that sends to the display unit, a reference beam, an erase beam, a readout beam, etc.

[0141] The display unit receives three-dimensional image information of an object from the input unit, records it on a hologram plate made of an optically addressed SLM, and can reproduce the three-dimensional image of the object. At this time, the three-dimensional image information of the object can be recorded by the interference of the input beam and the reference beam. The three-dimensional image information of the object recorded on the hologram plate can be reproduced as a three-dimensional image by the diffraction pattern generated by the readout beam, and the erase beam can be used to quickly remove the formed diffraction pattern. On the other hand, the hologram plate can move between the input position and the playback position of the three-dimensional image. [Effects of the Invention]

[0142] A holographic recording medium according to one embodiment of the invention not only exhibits excellent optical recording characteristics, but also demonstrates transparent optical properties and excellent reliability even in high-temperature and high-humidity environments. [Brief explanation of the drawing]

[0143] [Figure 1] This diagram schematically illustrates the setup of a recording device for hologram recording. Specifically, it schematically shows the process in which a laser of a predetermined wavelength is irradiated from a light source 10, and then irradiated onto a PP (hologram recording medium) 80 located on one side of the mirror 70, after passing through mirrors 20, 20', iris 30, spatial filter 40, iris 30', collimation lens 50, and polarized beam splitter (PBS) 60. [Modes for carrying out the invention]

[0144] The function and effects of the invention will be explained in more detail below through specific embodiments of the invention. However, these are presented as examples of the invention and do not limit the scope of the invention's rights in any way.

[0145] In the following manufacturing examples, examples, and comparative examples, the content of raw materials, etc., refers to the content based on solid content unless otherwise specified.

[0146] Manufacturing Example 1: Manufacturing of (meth)acrylic polyols In a 2L jacketed reactor, 132g of butyl acrylate, 420g of ethyl acrylate, and 48g of hydroxybutyl acrylate were added and diluted with 1200g of ethyl acetate. The reaction temperature was set to 60-70°C, and the mixture was stirred for 30 minutes to 1 hour. 0.42g of n-dodecyl mercaptan (n-DDM) was added, and the mixture was stirred for another 30 minutes. Subsequently, 0.24g of the polymerization initiator AIBN (azobis(isobutyronitrile)) was added, and polymerization was carried out at the reaction temperature for 4 hours or more until the residual acrylate content was less than 1%, thereby producing a (meth)acrylate copolymer with hydroxyl groups located in branched chains (weight-average molecular weight approximately 300,000, OH equivalent approximately 1802g / equivalent).

[0147] Example 1: Manufacture of photopolymer composition and holographic recording medium (1) Production of photopolymer compositions 1.27 g of poly(methylhydrosiloxane) (manufactured by Sigma-Aldrich, number average molecular weight: approximately 390, Si-H equivalent: approximately 103 g / equivalent) as a siloxane polymer and 11.12 g of (meth)acrylic polyol produced in Production Example 1 were mixed first (SiH / OH molar ratio = 2.0).

[0148] Then, 20 g of HR6042 (Miwon, refractive index 1.60) and 0.08 g of the photosensitive dye H-Nu640 (Spectra), 0.3 g of the co-initiators Borate V and 0.05 g of H-Nu254 (Spectra), 10 g of the fluorine-based compound represented by the following chemical formula a as a plasticizer, and 26 g of the solvent methyl isobutyl ketone (MIBK) were added, and the mixture was stirred in a paste mixer for about 30 minutes while blocking out light. Subsequently, a Karsted (Pt-based) catalyst was added for matrix crosslinking to produce a photopolymer composition. [ka]

[0149] (2) Manufacturing of holographic recording media The photopolymer composition was coated to a predetermined thickness onto a 60 μm thick TAC substrate using a Mayer bar, and dried at 80°C for 10 minutes. After drying, the thickness of the photopolymer layer was approximately 15 μm.

[0150] A diffraction grating was recorded using the setup shown in Figure 1. Specifically, after laminating the manufactured photopolymer layer onto a mirror, irradiating it with a laser allows for the recording of a notch filter hologram with periodic refractive index modulation in the thickness direction due to the interference of incident light L and light L' reflected by the mirror. In this example, the notch filter hologram was recorded with an incident angle of 0° (degree). A notch filter and a Bragg reflector are optical elements that reflect only light of a specific wavelength, and have a structure in which two layers with a difference in refractive index are periodically stacked to a constant thickness.

[0151] Examples 2-9 and Comparative Examples 1-3: Production of Photopolymer Compositions and Holographic Recording Media A photopolymer composition and a holographic recording medium were manufactured in the same manner as in Example 1, except that the components and content of the photopolymer composition were different as shown in Table 1 below.

[0152] [Table 1] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0153] Test Example: Performance Evaluation of Holographic Recording Media (1) Diffraction efficiency The diffraction efficiency (η) was calculated using Equation 1 below.

[0154] η(%)={P D / (P D +P T )}×100 (Equation 1) In equation 1, η is the diffraction efficiency, and P D This is the output power (mW / cm²) of the diffracted beam of the sample after recording. 2 ) and P TThis is the output power (mW / cm²) of the beam transmitted through the sample after recording. 2 )

[0155] (2) Refractive index modulation value (Δn) The refractive index modulation value (Δn) was determined using Equation 2 below and Bragg's equation.

number

[0156]

number

[0157] In the above formula, η is the reflectance diffraction efficiency (DE), d is the thickness of the photopolymer layer, λ is the wavelength of the incident light for recording (660 nm or 532 nm), θ is the angle of incidence of the incident light for recording, φ is the slant angle of the grating, Δn is the refractive index modulation value, n is the refractive index of the photopolymer, and Λ represents the period of the diffraction grating. In the examples and comparative examples, since the hologram was recorded using a notch filter method, θ (angle of incidence) and φ (slant angle of the grating) are all 0°.

[0158] (3) Hayes Haze was measured using a HAZE METER (Murakami Color Research Laboratory, HM-150) in accordance with JIS K7136. The measurement light was incident on the side surface of the substrate of the holographic recording medium.

[0159] (4) Peak changes First, the specific wavelength (or wavelength band) (A0) exhibiting the maximum reflectance (i.e., lowest transmittance) of the sample with the diffraction grating recorded was analyzed (analyzed at room temperature and under non-high humidity conditions). A UV-Vis (Ultra Violet-Visible) spectrometer was used for the analysis, and the analysis wavelength range was 300 to 1,200 nm.

[0160] Subsequently, the same sample was stored for 72 hours at a temperature of 60°C and a relative humidity of 90%, and the wavelength (or wavelength band) (A1) with the highest reflectivity (lowest transmittance) was recorded in the same manner. The peak change, which represents the degree of shift in the wavelength with the lowest transmittance before and after evaluation, was measured using Equation 3 below. At this time, it was assumed that the deformation of the sample (e.g., contraction or expansion) did not affect the surface grid (pitch) and occurred only in the direction perpendicular to the sample surface. Peak change = {|1-A1 / A0|} × 100 (Equation 3)

[0161] (5) Adhesion after aging After forming an adhesive layer on a glass substrate using tesa® 61563 (50 μm thick, TESA Corporation) as a rubber-based optically clear adhesive (OCA), the photopolymer layer of the sample on which the diffraction grating was recorded was laminated so that it was in contact with the adhesive layer. Subsequently, the obtained sample was cut to a width of 2.5 cm to prepare a sample in which the glass substrate, adhesive layer, photopolymer layer, and TAC substrate were laminated in that order.

[0162] After storing the prepared samples at 60°C and 90% relative humidity for 72 hours, the adhesive strength between the photopolymer layer and the adhesive layer was measured using a texture analyzer. The peel angle during adhesive strength measurement was 180°, and the peel speed was 5 mm / sec.

[0163] [Table 2]

[0164] Referring to Table 2, the holographic recording media produced in Examples 1 to 9 exhibited excellent diffraction efficiency and refractive index modulation values ​​and low haze, while also showing little change in the wavelength of maximum reflectivity even after exposure to high temperature / high humidity environments, demonstrating high adhesion and excellent reliability in high temperature / high humidity environments. In contrast, the holographic recording media produced in Comparative Example 2 had poor optical recording characteristics, haze, and reliability in high temperature / high humidity environments. The holographic recording media produced in Comparative Examples 1 and 3 had excellent optical recording characteristics but showed poor reliability in high temperature / high humidity environments.

[0165] This confirms that a holographic recording medium according to one embodiment of the present invention, by containing a fluorine-based compound of a specific structure, exhibits excellent optical recording characteristics, superior reliability even in high-temperature / high-humidity environments, and high transparency.

Claims

1. A holographic recording medium, A polymer matrix or its precursor formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol, A photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom, The photopolymer layer includes a fluorine-based compound, The fluorine-based compound includes a fluorine-based compound represented by the following chemical formula 1, 【Chemistry 1】 In chemical formula 1, Z1 and Z2 are independently -O-, -S-, or -NH-, At least one of R1 to R4 is a fluorine-containing substituent, which is a C1-C20 alkyl group substituted with two or more fluorines, a C3-C30 cycloalkyl group substituted with two or more fluorines, or a C6-C30 aryl group substituted with two or more fluorines. If R1 to R4 are not fluorine-containing substituents, each is independently a C1-C20 alkyl group, a C3-C30 cycloalkyl group, a C4-C30 heterocycloalkyl group, a C7-C40 cycloalkylalkyl group, a C6-C30 aryl group, a C4-C30 heteroaryl group, or a C7-C40 arylalkyl group, or a substituent in which one or more of the -CH2- groups are substituted with -O-, -S-, or -NH-. The fluorine-based compound is included in an amount of 20 to 200 parts by weight per 100 parts by weight of the polymer matrix. The peak change calculated by formula 3 below is 3% or less. Peak change = {|1-A} １ / A ０ |}×100 (Formula 3) In formula 3, A ０ This is the wavelength at which the holographic recording medium has the lowest transmittance in the wavelength range of 300 to 1200 nm. A １ This is the wavelength of the lowest transmittance measured after the holographic recording medium was exposed to a temperature of 60°C and a relative humidity of 90% for 72 hours. A holographic recording medium comprising a photopolymer layer laminated with an optically transparent adhesive layer, stored for 72 hours at a temperature of 60°C and a relative humidity of 90%, and then measured under conditions of a peel angle of 180° and a peel rate of 5 mm / sec, wherein the adhesive strength between the photopolymer layer and the adhesive layer is 500 gf / 2.5 cm or more.

2. The siloxane polymer comprises a repeating unit represented by the following chemical formula 2, 【Chemistry 2】 It includes the terminal group represented by the following chemical formula 3, 【Transformation 3】 In chemical formula 2, Multiple R １１ and R １２ These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. k is an integer between 1 and 10000. In chemical formula 3, Multiple R １３ ~R １５ These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. At least one repeating unit among the repeating units represented by Chemical Formula 2 and any one end group among the end groups represented by Chemical Formula 3, R １１ ~R １５ At least one of which is hydrogen, the hologram recording medium according to claim 1.

3. The holographic recording medium according to claim 1 or 2, wherein the (meth)acrylic polyol is a polymer having a structure in which a hydroxyl group is bonded to the main chain or side chain of a (meth)acrylate polymer.

4. The aforementioned photoreactive monomer is Benzyl (meth)acrylate, benzyl 2-phenyl acrylate, phenoxybenzyl (meth)acrylate, phenol (ethylene oxide) (meth)acrylate, phenol (ethylene oxide) ２ One or more monofunctional monomers selected from the group consisting of (meth)acrylate, O-phenylphenol (ethylene oxide) (meth)acrylate, phenylthioethyl (meth)acrylate, and biphenylmethyl (meth)acrylate, Bisphenol A (ethylene oxide) ２～１０ One or more polyfunctional monomers selected from the group consisting of di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisphenol orange (meth)acrylate, modified bisphenol orange (meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, phenol novolac epoxy (meth)acrylate, and cresol novolac epoxy (meth)acrylate, or A holographic recording medium according to claim 1 or 2, comprising a mixture of two or more of these.

5. The holographic recording medium according to claim 1 or 2, wherein the photoinitiator system comprises a photosensitive dye and a coinitiator.

6. The aforementioned co-initiator contains a borate anion represented by the following chemical formula 4, 【Chemistry 4】 In chemical formula 4, X １ ~X ４ Each of these is independently a substituted or unsubstituted C1-C20 alkyl group, a C2-C20 alkenyl group, a C6-C30 aryl group, a C7-C30 arylalkyl group, a C7-C30 alkylaryl group, or an allyl group. X １ ~X ４ The holographic recording medium according to claim 5, wherein at least one of the groups is not an aryl group.

7. In chemical formula 1, if R1 to R4 are not fluorine-containing substituents, R1 to R4 are each independently an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a phenyl group, a benzyl group, a pyridinyl group, a pyrimidinyl group, a methoxymethyl group, a methoxyethyl group, a methyl mercaptoethyl group, a methylaminoethyl group, -(CH2CH2O)c1CH3, -CH2O(CH2CH2O)c2CH3, a cyclohexyloxyethyl group, a cyclohexyl mercaptoethyl group, or a phenyloxyethyl group. The hologram recording medium according to claim 1 or 2, wherein c1 is an integer from 1 to 5, and c2 is an integer from 1 to 4.

8. In chemical formula 1, R １ The hologram recording medium according to claim 1, wherein is a fluorine-containing substituent.

9. The holographic recording medium according to claim 1, wherein the fluorine-containing substituent is a linear alkyl group having 1 to 20 carbon atoms substituted with two or more fluorines, a cycloalkyl group having 3 to 12 carbon atoms substituted with two or more fluorines, or an aryl group having 6 to 14 carbon atoms substituted with two or more fluorines.

10. The fluorine-containing substituent is -(CH ２ ) ａ (CF ２ ) ｂ CHF ２ ,-(CH ２ ) ａ (CF ２ ) ｂ CF ３ or decafluorocyclohexyl group, a is an integer between 0 and 3. The hologram recording medium according to claim 1, wherein b is an integer from 0 to 19.

11. In chemical formula 1, R １ ~R ４ If R is not a fluorine-containing substituent, １ ~R ４ Each of these is independently a linear alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a heterocycloalkyl group having 4 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, a heteroaryl group having 4 to 12 carbon atoms, an arylalkyl group having 7 to 16 carbon atoms, or -(R ５ -Y １ ) ｃ -R ６ And, R ５ This is an alkylene group having 1 to 6 carbon atoms. R ６ These are C1-C6 alkyl groups, C3-C12 cycloalkyl groups, or C6-C14 aryl groups. Y １ is -O- or -S-, c is an integer between 1 and 12. When c is 2 or greater, R ５ The hologram recording medium according to claim 1, wherein the elements are identical or different from each other.

12. A fluorine-based compound represented by chemical formula 1 includes one or more fluorine-based compounds selected from the group consisting of fluorine-based compounds represented by the following chemical formulas 1-1 to 1-9. 【Transformation 5】 【Transformation 6】 【Transformation 7】 【Transformation 8】 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 In chemical formula 1-1, Z ａ１ and Z ｂ１ These are, independently, -O-, -S-, or -NH-, R ａ１ and R ｂ１ Each of them is independent of CF ３ or CHF ２ And, R ｃ１ and R ｃ２ Each of these is an alkylene group having 1 to 6 carbon atoms, Y ａ１ and Y ａ２ Each of them is independent of -CH ２ -, -O-, -S-, or -NH- R ｄ１ and R ｄ２ Each of these is independently an alkylene group having 1 to 4 carbon atoms. R ｅ１ and R ｅ２ Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyclohexyl group, or a phenyl group. p1 and p2 are each independent integers between 0 and 9. q1 and q2 are each independent integers between 0 and 3. In chemical formula 1-2, Z ａ２ and Z ｂ２ These are, independently, -O-, -S-, or -NH-, R ａ２ CF ３ or CHF ２ And, R ｃ３ ~R ｃ５ Each of these is an alkylene group having 1 to 6 carbon atoms, Y ａ３ ~Y ａ５ Each of them is independent of -CH ２ -, -O-, -S-, or -NH- R ｄ３ ~R ｄ５ Each of these is independently an alkylene group having 1 to 4 carbon atoms. R ｅ３ ~R ｅ５ Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyclohexyl group, or a phenyl group. p3 is an integer from 0 to 9. q3 to q5 are each independent integers between 0 and 3. In chemical formula 1-3, Z ａ３ and Z ｂ３ These are, independently, -O-, -S-, or -NH-, R ａ３ , R ｂ２ and R ｂ３ Each of them is independent of CF ３ or CHF ２ And, R ｃ６ This is an alkylene group having 1 to 6 carbon atoms. Y ａ６ is, -CH ２ -, -O-, -S-, or -NH- R ｄ６ This is an alkylene group having 1 to 4 carbon atoms. R ｅ６ These are hydrogen, an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, or a phenyl group. R ｆ１ and R ｆ２ These are, independently, hydrogen or fluorine, p4 to p6 are each independent integers from 0 to 9. q6 is an integer between 0 and 3. In chemical formula 1-4, Z ａ４ and Z ｂ４ These are, independently, -O-, -S-, or -NH-, R ａ４ 、 R ａ５ 、 R ｂ４ 以及 R ｂ５ 各自独立地为 CF ３ 或 CHF ２ , R ｆ３ ~R ｆ６ These are, independently, hydrogen or fluorine, Pages p7 to p10 are each independent integers from 0 to 9. In chemical formula 1-5, Z ａ５ and Z ｂ５ These are, independently, -O-, -S-, or -NH-, R ａ６ and R ａ７ are each independently CF ３ or CHF ２ and R ｃ７ and R ｃ８ Each of these is an alkylene group having 1 to 6 carbon atoms, Y ａ７ and Y ａ８ Each of them is independent of -CH ２ -, -O-, -S-, or -NH- R ｄ７ and R ｄ８ Each of these is independently an alkylene group having 1 to 4 carbon atoms. R ｅ７ and R ｅ８ Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyclohexyl group, or a phenyl group. p11 to p12 are each independent integers from 0 to 9. q7 and q8 are each independent integers between 0 and 3. In chemical formula 1-6, Z ａ６ and Z ｂ６ These are, independently, -O-, -S-, or -NH-, R ａ８ ~R ａ１０ Each of them is independent of CF ３ or CHF ２ And, R ｃ９ This is an alkylene group having 1 to 6 carbon atoms. Y ａ９ is, -CH ２ -, -O-, -S-, or -NH- R ｄ９ This is an alkylene group having 1 to 4 carbon atoms. R ｅ９ These are hydrogen, an alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, or a phenyl group. Pages 13 through 15 are each independent integers from 0 to 9. q9 is an integer between 0 and 3. In chemical formula 1-7, Z ａ７ and Z ｂ７ These are, independently, -O-, -S-, or -NH-, R ｂ９ , R ｃ１０ and R ｄ１０ These are, independently, a decafluorocyclohexyl group, a phenyl group, a pyridinyl group, a pyrimidinyl group, or a methoxyethyl group. In chemical formula 1-8, Z ａ８ and Z ｂ８ These are, independently, -O-, -S-, or -NH-, R ｂ１０ , R ｃ１１ and R ｄ１１ These are, independently, a 2,2,3,3,4,4,5,5-oxafluoro-1-pentyl group, a decafluorocyclohexyl group, a phenyl group, or a methoxyethyl group. In chemical formula 1-9, Z ａ９ and Z ｂ９ These are, independently, -O-, -S-, or -NH-, R ａ１１ and R ｂ１１ Each of them is independent of CF ３ or CHF ２ And, R ｃ１２ and R ｄ１２ These are, independently, a phenyl group or a benzyl group. The hologram recording medium according to claim 1 or 2, wherein p16 and p17 are each independently integers from 0 to 9.

13. The hologram recording medium according to claim 1 or 2, wherein the fluorine-based compound is contained in an amount of 25 to 180 parts by weight per 100 parts by weight of the polymer matrix.

14. The hologram recording medium according to claim 1 or 2, wherein when a notch filter hologram is recorded, the diffraction efficiency of the hologram recording medium is 70% or more.

15. The holographic recording medium according to claim 1 or 2, wherein the thickness of the photopolymer layer is 5 to 30 μm, and the refractive index modulation value of the holographic recording medium is 0.020 or greater.

16. The hologram recording medium according to claim 1 or 2, wherein the haze of the hologram recording medium is 2% or less.

17. An optical element comprising a holographic recording medium according to claim 1 or 2.

Images